Process of cracking hydrocarbon oils



J. DELATTRE-SEGUY PROCESS OF CRACKING HYDROCARBON OILS Filed Dec. 24, 1927 21/ z in 655 n [07". LJaR 2061a fireffe Patented Dec. 12, 1933 1,939,281- PROCESS or CRACKING HYDROCARBON' Jean Delattre-SeguyL Chicago, Ill.,. assignor .to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application December 24, 1927 Serial :No.-242,435

7 laim 6%60.)

This invention relates to improvements in process of cracking hydrocarbon oils, and its novel features are more particularly directedto certain improvementsin so calledev'apor phase, cracking.

.With .the increasing advent of combustion engines having high compression ratios, it has been foundjdesirable to use .motor fuels containing what arecommonly known} as anti-knock compounds. These anti-knock compounds are in some in- 19 stances increased or produced by the formation of a relatively large percent of unsaturates in the gasoline or motor .fuel. The present invention is adapted in its novel'features to produce these antiknock compounds in part, at'least, through the cracking of the vapors in what is generally known as vapor phase cracking.

The invention is also adapted as part of a continuous process to produce gasoline or gasoline like bodies, which are relatively low in unsaturates.

.29 In addition, the process can be so operated as to more or less quantitatively control the percent of unsaturates.

In this application, as will hereafter more clearly appear, I have described my basic process, together with various specific examples which may be carried out utilizing the broader idea of the invention, but with modified details depending upon the results desired or the character of 'oil under treatment.

This process is of such a character that the raw chargingstockQwhether gas oil, fueloil, crude or reduced crude; or the like, may be first subjected to the well known so' called liquid-vapor phase cracking under pressure and certain of the gasoline constituents so formed may then, if desired, be removed from the system, whilethe reflux'condensate from such pressure cracking may then be subjected to vapor phase cracking,'at atmospheric or reduced pressures.

By such operation the reflux condensate so formedis preferably separated from the carbon containing residues, and becomes a relatively clean charging stock for the vapor phase cracking operation. 7

At the same time, if desired, the residue produced from the liquid-vapor phase pressure operation may be flashed and the flashed vapors from the residue also become a highlydesirable and relatively clean charging stock for the vapor phase operations. The process maybe so carried out that the reflux from the main pressure cracking operation may be independently treatedfrom the vapors produced by the flashing of the residuum, or they may be treatedtogether, as a common vapor phase charging stock.

per phase part of the operation in reality coinpletes the maximum formation of anti-knock from the pressure part of the process will insuch process as liquid-vapor pressure operation and Another feature of this invention is that the hydrocarbons which .are subjected to the vapor phase cracking, have prior thereto already been so treated by the pressure process as to more or less crack them, whereby the subsequent cracking Q0 of such reflux or vapors in the vapor phase part of the process, is much easier than would be the case were the raw charging stock initially subjected to straight vapor phase cracking.

' It iswellknown in present vapor phase crackthat the fuel consumption is high and the incondensable gas 'loss is large. In addition, in presenttypesof vapor phase cracking the carbon production'is' high. By means of the present invention the fuel consumption is materially '10 lowered, the gas losses materially reduced, due in part'to the ability tocrack in the vapor phase at. a lower temperature than has heretofore been done, and ,also the carbon production is materially lessened because of the previously prepared charging stock for the vapor phase operations. These advantages? are all obtained without in any way lessening the production of the desirable anti-knock compounds, but quite the contrary such anti-knock compounds are produced in excess of that heretoforejpossible andwith much more satisfactory cracking conditions.

It .is to be understood that by means of the present process the oil is so preliminarily treated prior to the vapor phase operation that it is in prime condition for vapor phase cracking, because it has already been initially cracked with the ,formationof some unsaturates and the va- 90' compounds alreadypreviously started. Heretofore vapor phase processes have only been partially successful on gas oil, but by the present invention heavy fuel oils or crude petroleum may be cracked to obtain the maximum amount of gasoline, and certain of the constituents thereof converted into a maximum amount of antiknock compounds. Another feature of 'the invention ,is that the reflux produced from" the vapor phase cracking, may, if desired, be mixed with the raw charging stock in the pressure part; of the process, and

inasmuch as this reflux contains in itself a large amount of anti-knock compounds the gasoline case be produced with a large amount of antiknock compounds.

I have above referred to a certain part of the another part as vapor phase cracking at atmosshown in the drawlngf pheric pressure. It is to be understood, however, that in its broader'aspect the invention is' 7 not limited to the vapor phase cracking at atmospheric pressure, as good results may be 013 tained even though the vapor phase cracking partof the operation is carried out at 'superatmospheric or subatmospheric pressure. For example, the liquid-vapor pressure part of the process may be at say 100 lbs. upwards and the vapor phase cracking at pressures of 50 lbs. or

lower. p

It is to be understood that these figures are merely illustrative andin no sense intended to limit the scope of invention on the degree of' pressure.

The invention will be more clearly understood from the following description, reference being had to'the accompanying drawing.

This drawing shows a diagrammatic illustra-' tion of an apparatus and in my opinion a novel form of apparatus suitable for carrying out the invention. It is to be understood that this 'diagrammatic drawing is not to scale or intended to be.

Referring to the drawing, a cracking coil 1 is positioned in a suitable furnace 2. Raw oil is supplied to the coil 1 through feed line 3' and feed pump '4, leading to any suitable source of supply; The oil passes from will to transfer line 5, having throttle valve 6, into expansion chamber 7. The vapors pass out of expansion chamber 7 through'vapor line 8} andthence, if

desired, into the lower side of dephlegmator 9. Throttle .valve 10 is interposed in line 8 .for a purpose hereinafter described. From the top of the dephlegmator the vapors may pass through vapor outlet pipe 12, into condenser coil 14, and then to receiver 15. Receiver 15 is provided with gas outlet control valve 16, and liquid draw ofi control valve 17. a 1 The temperature of thejdephlegmator may be controlled either by introducing raw oil directly into the vapors in the dephlegmator through pipe 18, having control valve 19; or in the event it is undesirable to introduce the raw oil directly to the dephlegmator, as is. true in certain cases hereinafter described, then the rawoil' may be fed through a closed coil 20, which closed coil may, if desired, lead the oil after its passage therethrough, to the pump4.

The reflux condensate from the dephlegmator 9 is drawn off. through'the lower end thereof through pipe 21, and thence may berreturned through lines 21 and 2 2 and pump 23 tothe raw oil feed line 3. A by-pass,'2%1'may be provided in line 22 around the pump. 23,,suitable valves 25 being provided as shown. f

In the line 21, is provided a throttle valve 26. The reflux may also pass through line 27 and branch 28 to vapor phase feed line '29, hereinafter referred to. t

A pump 30 maybe interposed in line 27, and

' a by-pass line 31 around the pump may also be provided, throttle valves 32 being interposed as The reflux condensate may v instead of being sent through branch 28, after it'reaches 27, be diverted through pipe 33,- having throttle valve 34, and then combined with the residuum-drawn off from chamber 7 by means ofdraw-off line 35 and branch 36, the latter leading to the residuum flash chamber,37.- .A valve 38 is interposed in the line 36 and a throttle valve 39 is interposed in an extension of the line 35below the juncture of the line 35 with the line 36,

thencethrough pump 68 to line 69.

whereby some of the residuum may be drawn entirely out of the system, if desired.

The vapors which are flashed from the flash chamber 37 pass out through the upper part thereof through pipe 40, having throttle valve 41 and thence to the line 29. At the lower end of the flash chamber 37 is a residuum draw off 42 having throttle control valve 43.

' In certain cases the flash chamber 37 may be by-passed and the chamber 7 used as a combined reaction or expansion and flash chamber.

In such cases all of the vapors from chamber 7 may either pass to the dephlegmator 9, or they -may pass directly to line 29 by means of a branch .furnace 48. The outlet end of the coil connects through delivery line 49 having throttle valve 50 intochamber 5 1. This separating chamber 51 is provided with a carbon or residue draw ofi pipe 52, having throttle valve 53, and with vapor outlet pipe 54, having throttle valve 55. The pipe 54 leads to the side of dephlegmator 56. The temperature in this dephlegmator may be controlled either by introducing raw oil directly into dephlegmator 56, by pipe 57., having control valve 58, or if desired raw oil may be passed through the closed coil 59, and thence if desired led to the feed pump 4. The raw oil is not introduced directly into either dephlegmator unless it is desired to send it to the pressure cracking coil 1, or unless it is of such a character that it is so clean a charging stock that it can be passed directly to the vapor phase cracking coil 47, without materially increasing carbon formation in the vapor phase coil.

The vapors pass. out of dephlegmator 56 through vapor line 60 to condenser coil 61 and thence to receiver 62, which is provided with gas outlet control .valve 63 and liquid outlet control valve-64. If desired the vapors from dephlegmator 9 may also pass into receiver 62, thus eliminating receiver 15. To this end a vapor pipe 65 having control valve 66 may lead from the line 12 to the line 60.

The reflux condensate from dephlegmator 56 passes out of the lower end through pipe 67, and The by-pass 70 may be provided around the pumpwith the usual valves 71. The reflux from line 69 may be passed directly, if desired, to line 29, by means of pipe 72, havingthrottle valve 73 and line 28,

or if desired it may pass via line 72 into line 33 by opening the valve 34 and closing the valve 74, in the line 28, or the condensate may be passed from the pipe 69 into the line 22 by closing the valve 73 and opening the valve 75. The reflux from either dephlegmator may be drawn out of the system through branch 77 having throttle valve 78, or branch 79, having throttle valve 80. V

Describing now a desirable method of carrying out the process, the raw charging stock to be treated is subjected in the main cracking coil to cracking conditions-cf temperature and pressure, say to'a pressure of 200 1bs.'or above, and heated to a transfer temperature of say 750 to 900 F.

The stock used may be, for example, a topped the pressure of that 'ofithe-cracking coil, say

from 50 lbs.- down-to substantially: atmospheric" pressure. The flashed vapors-passout' of the phase cracking" coil, where' it is subjected" to vapor phase cracking. In order tomake the inventionmore clear, I will describe the-process carried out inthis detail.

the'feed line 3 and into theheating coil 1. It

pressures .heretofore'referred tor--- The heated oil thencepasses' through-tlie -re-..

duc'ing' valve 6into-combined: reaction and flash! ingl chamber 7, where" the pressure is reduced as heretofore-stated. All ofthe vapors, either those produced 'inthe cracking coill-or those pm. duced by the flashing due to thereduced pres sure, then pass through the line -8 'into the dephle'gmator 9. The residue is drawn ofl through line 35 and through line 39. In such case the flashing chamber 3'7 is cut out of the system by suitably regulating the valvesheretofore referred to. The vapors in the dephlegmator 9 are subjected to reflux condensing action and such reflux condensate returned through the lines 21, 31, 27, 28 and 29 into the vapor phase cracking coil 4'7. The temperature of the dephlegmator 9 may be such that substantially only gasoline-like constituents will pass out of the top of dephlegmator 9, while all the balance will be drawn off as reflux condensate. As it passes through the vapor phase cracking coil 47 the oil is subjected to further cracking, say at a temperature of 1000 F. or above, and a substantial portion of it converted into unsaturates, aromatics or other anti-knock compounds. From the coil 47 the oil passes into the separating chamber 51 where any carbon or heavy oil will tend to drop out and may be drawn out of the system The vapors will pass out through the pipe 54 into the dephlegmator 56. The temperature of this dephlegmator may be controlled as desired, by means of the raw oil heretofore referred to. The reflux condensate from the dephlegmator 56 may be passed back through the lines shown to the main cracking coil 1, or drawn out of the system. The uncondensed vapors will pass out of dephlegmator 56 through line 60 and condenser coil 61 into the receiver 62. All of this system except the cracking coil 1 may be maintainedeither under substantially atmospheric pressure, or at a pressure much lower than that towhich the oil in the main coil 1 is subjected. Also in carrying out the process a pressure of 300 lbs. may be maintained in coil 1, a pressure of say 100 lbs. on the flash chamber 7 and dephlegmator 9, while the vapor phase cracking coil 47 and its associated parts may be maintained at substantially atmospheric pressure, or even under a vacuum (in the last case a vacuum pump not shown will be connected to receiver 62). These differential pressures may be of course controlled by suitably operating the valves heretofore described, and it is not necessary to point them out here in detail.

The process above described is particularly desirable where the original raw charging stock is not heavy in carbon formation, as for example, with a relatively clean gas oil or a relatively manner somewhat 5 more I in light..fuel oil, and, also where it isdesirable to make a maximum amount of the anti-knock compounds and convert a minimum amount of the raw charging stock into saturated compounds. Thismethod of carrying out the process just above. described may also be desirable in certaincases where the minimum amount of. ap-' paratus is,desired. Inzthis process also more of thegasolineproduced by the pressure cracking i 1 operation is separated out and not subjected to,

Therawcharging stock may be passed through line '57 into the dephlegmator-56 and" thence mixed with the reflux' condensate-therefrom to the-vapor phase cracking than would bethe case were the chamber 37 used as a flash chamber.

Certainfeatures of my invention disclosed. but

not claimedherein constitute the claimed subject .1, In processes for converting high boiling point oils intolowboiling point oils in which the high boiling point oil is subjected to pressure distillatioriina pressure distillation zone, vapors and unvaporized liquid separately removed from ,the pressure distillation zone, the unvaporized liquid introducedwhile .hot into a zone of lower pressure wherein substantial distillation thereof is effected by the contained heat of the oil, the improvement which comprises introducing to the unvaporized liquid oil removed from the pressure distillation zone prior to further distillation in said zone of lower pressure a lighter oil of lower temperature than said removed unvaporized liquid oil, removing vapors from said zone of lower pressure, and subjecting the same to vapor phase cracking.

2. A hydrocarbon oil cracking process which comprises heating the oil to cracking tempera .flashed vapors and vapors evolved from the lower boiling oil and subjecting the same to a gasolineproducing vapor phase cracking operation, and condensing the resultant gasoline vapors as a product of the process.

3. A hydrocarbon oil cracking process which comprises heating the oil to cracking temperature under pressure and separating the same into vapors and unvaporized oil, flash distilling the unvaporized oil in a flashing zone by pressure reduction, removing resultant flashed vapors from the flashing zone and subjecting the same to a gasoline-producing vapor phase cracking operation, dephlegmating the vapor phase cracked vapors to condense heavier fractions thereof, introducing resultant reflux condensate to said flashing zone to be vaporized therein, the vapors thus evolved from the reflux condensate passing to the vapor phase cracking operation in admixture with the flashed vapors, and condensing the dephlegmated gasoline vapors as a product of the process.

4. A process for cracking hydrocarbon oil, consisting in subjecting the oil to conversion conditions of temperature and pressure, separately removing the vapors and the residue, subjecting the vapors to dephlegmation thereby producing reflux condensate, combining said reflux condensate and said residue and reducing the pressure on the mixture to permit flash distillation of vapors therefrom, andisubj'ecti'ng" the vapors so distilled to a vapor phase cracking reaction.

5. A process for cracking hydrocarbon oil, consisting in subjecting the oil to conversion conditions of temperature and pressure, separately removing the vapors and the residue, subjecting the vapors to dephlegmationthereby producing reflux condensate, combining said reflux condensate'and said residue and reducing the pressure on the mixture to permit flash distillation of vapors therefrom, and subjecting the vapors so distilled to a-vapor phase cracking reaction, dephlegmating the vapor phase cracked vapors thereby forming a second reflux condensate, and returning said second reflux condensate to the process for retreat-ment.

6. A process for cracking hydrocarbon oil, consisting in subjecting the oil to conversion conditions of temperature and pressure, separately removing the vapors and the residue, subjecting the vapors to dephlegmation thereby producing reflux condensate, combining said reflux condensate and said residue and reducing the pressure on the mixture to permit flash distillation of vapors therefrom, and subjecting the and reducing the pressure on the mixture to permit flash distillationof vapors therefrom, and subjecting the vapors so distilled to a vapor phase cracking reaction, dephlegmating the vapor phase cracked vapors by heat exchange with charging oil for the process thereby forming a second reflux condensate, and preheating the charging oil, and passing the preheated charging oil and'said second reflux condensate to said conversion zone.

JEAN DELAT'IRE-SEGUY. 

